A search engine or search service is a program designed to help find information stored on a computer system such as the World Wide Web, a network, intranet, or personal computer. For example, a search engine may allow a user to search for content meeting specific criteria, such as those containing a given word or phrase, and retrieves a list of references that match those criteria. Search engines may use regularly updated indexes to help expedite the searches.
Search engines attempt to provide the user with search results consisting of relevant documents. To determine relevancy, many search engines use search methods such as link popularity and PageRank. In such methods, the number of other web sites and web pages that link to a given page (i.e., data file) may be taken into consideration in determining the relevancy of that particular page, on the premise that desirable pages are linked to more often than less desirable pages. For example, the number of linking pages and the number of links on these pages contribute to the PageRank of the linked data file. Such search engines then order their search results according to the PageRank. PageRank is but one of many criteria used to determine relevancy. For example, when searching through various data files stored on a database, a search tool may determine the relevance of a data file based on the number of times a search term is repeated in the data file. Further still, other search tools may determine the relevancy of a data file based where the search term is located in the date file (e.g., file name).